KR20210148194A - Apparatus and method for manufacturing high-strength, high-modulus polyolefin thin film and high-strength, high-modulus polyolefin thin film - Google Patents

Abstract

The present invention provides an apparatus and method for manufacturing a high-strength, high-modulus polyolefin thin film and a high-strength, high-modulus polyolefin thin film. An apparatus for producing a high-strength, high-modulus polyolefin thin film includes a melt extruder, a cooling system, a tensioning system, and an extraction system arranged sequentially. A method for producing a high-strength, high-modulus polyolefin thin film is to melt and plasticize a polyolefin resin and a solvent in a melt extruder, extrude it through a die head, and then achieve heat-induced phase separation in a shaping roller and a cooling tank to obtain a cast sheet, followed by a multi-step combination and obtaining the high-strength, high-modulus polyolefin thin film through tensioning with a tensile system, extraction with an extraction system, and post-treatment. A high-strength, high-modulus polyolefin thin film is prepared by the above method for producing a high-strength, high-modulus polyolefin thin film. The polyolefin thin film produced by the apparatus and method provided in the present invention achieves ultra-high magnification tensile, and the obtained thin film has excellent uniformity, strength, and heat shrinkage performance.

Description

Apparatus and method for manufacturing high-strength, high-modulus polyolefin thin film and high-strength, high-modulus polyolefin thin film

The present invention is filed on the basis of a Chinese patent application with an application number of 201911132107.0 and an filing date of November 19, 2019, claiming the priority of the Chinese patent application, the entire contents of the Chinese patent application being incorporated herein by reference do.

The present invention relates to the field of a polyolefin thin film, and more particularly, to an apparatus for manufacturing a high strength, high modulus polyolefin thin film, and a high strength, high modulus polyolefin thin film.

Wet lithium-ion battery thin film is currently one of the important building materials for liquid lithium-ion batteries, especially power batteries and advanced 3C digital batteries. Due to advantages such as low cost and high strength, polyolefin thin films have cost-effective advantages over conventional materials.

Existing methods for wet polyolefin thin film production use processes such as plastic extrusion casting, single asynchronous or synchronous tensile, extraction drying, secondary transverse tensile shaping, and winding. In order to ensure the extraction cooling effect after plasticizing extrusion, the thickness of the cast sheet generally does not exceed 2 mm; The bidirectional (MD/TD) magnification of single asynchronous tensioning or synchronous tensioning bidirectional tensioning does not exceed 10/10.

In the tensile process of the prior art, if the transverse tensile magnification is too large, the thin film middle part is greatly sagged due to the gravitational action, so that the thin film scrapes the device, or there is a serious problem that the force is applied unevenly in the transverse direction; With single synchronous tensioning, the transverse direction has the above-mentioned problems similar to single asynchronous tensioning; In addition, in the longitudinal tensioning of the bidirectional synchronous tensioning machine, the longitudinal magnification is achieved through the interval of chain clip change, calculated with the initial chain clip spacing of 0.05m, the longitudinal magnification should reach 100 times, The maximum gap between the chain clips should reach 5 m, and if the gap is too large, the middle part of the film will be concave, which will not help to receive heat, but will also bring a large limiting effect, which could not produce a passed film. Therefore, the current mainstream single asynchronous or synchronous tensioning machine process, the thin film cannot achieve the tension at ultra-high magnification, generally stays below 100 times; A thin film obtained with a low tensile magnification has problems with insufficient strength and low modulus.

In view of this, the present invention is specifically submitted.

It is an object of the present invention to provide an apparatus and method for manufacturing a high-strength, high-modulus polyolefin thin film and a high-strength, high-modulus polyolefin thin film to solve the above problems.

In order to achieve the above object, the present invention specifically uses the following technical solutions. An apparatus for producing a high-strength, high-modulus polyolefin thin film includes a melt extruder, a cooling system, a tensioning system, and an extraction system arranged sequentially;

The tensioning system includes a transverse tensioner for transversely tensioning an object to be tensioned, a longitudinal tensioner for tensioning the object to be tensioned in the longitudinal direction, a slitting machine for cutting the object to be tensioned, and a bidirectional tensioning machine for tensioning the object to be tensioned in both directions. Including many in synchronous tensioners.

Through multi-step tensioning and cutting, it solves the problem of thin film deflection due to gravitational action during the tensioning process, which limits the tensile magnification of a single synchronous bidirectional tensile or single asynchronous tensile machine to achieve up to 100*100 times area tensile magnification. to obtain a high-strength, high-modulus thin film.

Preferably, the apparatus for manufacturing the high-strength, high-modulus polyolefin thin film further includes a system such as a secondary transverse tensioning system and a thermal forming system for diaphragm contraction.

Preferably, the cooling system comprises a support roller, a shaping roller, a cooling roller and a cooling tank;

The shaping roller is installed between the support roller and the cooling roller, the support roller is for attaching the melt of the die head of the melt extruder to the surface of the shaping roller, the lower part of the shaping roller is in the cooling tank installed, and the cooling roller is for cooling the cast sheet processed by the shaping roller.

The cooling effect of the casting sheet cooling system for the large thickness of the casting sheet is not good, causing a large difference in the thermal history of the front and back sides of the thin film, resulting in a large difference in performance; Due to the low heat transfer coefficient of the cast sheet, if the cast sheet is thick, if no forced cooling action is taken on the back side, the back side cooling rate is too slow, which may form large lamellas or spheroids. The difference is magnified, and the cooling system provided by the present invention solves the problem that a conventional chill roll system is not suitable for a large-thickness cast sheet (the existing chill-roll system secures its cooling effect when processing a small-thickness cast sheet) can be effectively solved.

Preferably, said tensioning system comprises said longitudinal tensioner, said transverse tensioner, said slitting machine and said bidirectional synchronous tensioner installed sequentially; The slitting machine is for cutting the thin film tensioned by the transverse tensioning machine.

The width of the first tensioned thin film is large, and when performing secondary tensioning, the thin film is cut to achieve a large transverse tensile magnification.

Preferably, it further comprises a steering device installed behind the slitting machine;

Preferably, the bidirectional synchronous tensioner is installed in plurality;

Preferably, the bidirectional synchronous tensioner is installed in three stacks along the height direction;

Preferably, the bidirectional synchronous tensioner is provided with a heating oven and a cooling oven, the temperature accuracy of the heating oven is ±0.5° C., and the uniformity of the wind speed is ±1 m/s.

When performing secondary tensioning after cutting, it must enter along the center of the machine, and the existing machine processing process cannot achieve that the thin film enters a plurality of side-by-side two-step tensioners, and the present invention installs a steering device The cut thin film is steered several times to smoothly enter the two-stage tensioner. To reduce the site area, the bi-directional synchronous tensioner can also be designed with a multi-layered layout structure. By controlling the temperature accuracy of the heating oven and the uniformity of the wind speed, the uniformity of the thin film during tensioning can be ensured.

Optionally, the brewing system comprises one or several groups of brewing tanks, each group of said brewing tanks all equipped with different groups of drafting rollers and ultrasonic generators.

Multiple groups of drafting rollers are installed to allow the simultaneous introduction of multi-layer thin films into a single brewing tank, thereby avoiding disposing of multiple brewing tanks at the same time, reducing equipment investment and building investment.

A method for producing a high-strength, high-modulus polyolefin thin film,

Polyolefin resin and solvent are melt plasticized in a melt extruder, extruded through a die head, and then heat-induced phase separation is achieved in a shaping roller and a cooling tank to obtain a cast sheet, which is then tensioned by a multi-stage combination of tensioning system, extracted by an extraction system and and obtaining the high-strength, high-modulus polyolefin thin film through post-treatment.

Preferably, the thickness of the melt extruded by the die head is 2 mm-10 mm.

A large-thickness melt can be used to obtain a large-thick cast sheet, and it can be ensured that the thin film is stretched at a large magnification to have excellent properties such as high strength and high modulus.

Preferably, the tensioning method of the tensioning system comprises:

sequentially performing longitudinal tension 1-10 times, transverse tension 1-10 times and bidirectional synchronous tension (1-10)*(1-10) times; or,

sequentially performing 1-10 times longitudinal tension, 1-10 times transverse tension, and repeatedly performing 1-10 times longitudinal tension and 1-10 times transverse tension once; or,

Two consecutive independent bidirectional synchronous tensioning (1-10)*(1-10) folds; or,

and sequentially performing bidirectional synchronous tension (1-10)*(1-10) times, longitudinal tension 1-10 times, and transverse tension 1-10 times.

The formed cast sheet achieves ultra-high magnification tensile in the longitudinal and transverse product relation through different combination methods such as longitudinal tension, transverse tension, longitudinal and transverse synchronous tensioning. Bidirectional synchronous tension (1-10)*(1-10) times refers to 1-10 times in the transverse direction and 1-10 times in the longitudinal direction.

Optionally, the post-treatment includes drying, transverse puncture tensioning, longitudinal and transverse bidirectional shrinkage treatment and thermal shaping performed sequentially;

Preferably, when carrying out the extraction, the tensile pieces are not pre-cut.

Transverse puncture tension can ensure that the thin film has an appropriate porosity; The longitudinal and transverse bidirectional shrinkage treatment and thermal shaping give up the conventional transverse unidirectional shrinkage treatment method, so that the longitudinal and transverse directions of the thin film material can be contracted at the same time, improving the heat shrinkage stability in both directions; In the case of extraction drying, the tensile pieces are not pre-cut, and through the greater tension of the thick pieces, the transverse shrinkage of the thin film during the extraction process is suppressed, and the extraction shrinkage increases the transverse polarity of the thin film, and the uniformity Due to this bad problem, it seriously affects the conformability and safety reliability of lithium-ion batteries.

The high-strength, high-modulus polyolefin thin film is prepared by the method for producing the high-strength, high-modulus polyolefin thin film;

Preferably, the thickness of the high-strength, high-modulus polyolefin thin film is 2-100 μm, the air permeability is 10-300 s/in ² * 100 cc, the tensile strength is 300-2000 MPa, the non-puncture strength is 50-300 gf/μm, and the porosity is is 25-75%, and the modulus is 2 GPa to 30 GPa.

Compared with the prior art, the advantageous effects of the present invention are as follows.

Install cooling system and multi-stage tensioner to achieve large-scale tensioning; In the method provided by the present invention, the area tensile magnification is greatly improved to the level of 10000 times, and in this way, the orientation, crystallization, fiber refining, specific strength of the thin film material is greatly improved, and the tensile strength at break of the thin film material is reduced. A polyolefin thin film material of ultra-high strength and ultra-high modulus is formed.

In order to more clearly explain the technical solutions of the embodiments of the present invention, the drawings required in the following embodiments are briefly introduced. It should not be considered, and for those of ordinary skill in the art, other related drawings may be obtained based on these drawings under the premise that there is no need to strive for inventive step.
1 shows a schematic diagram of a cooling system provided by an embodiment;
2 shows a schematic diagram of a longitudinal tensioner provided by an embodiment;
3 shows a schematic diagram of a transverse tensioner provided by an embodiment;
Fig. 4 shows a schematic diagram of a slitting machine and a steering device provided by the embodiment;
Fig. 5 shows a schematic diagram of a bidirectional synchronous tensioner provided by the embodiment;
6 shows a schematic diagram of an extraction tank provided by an embodiment;
7 shows a scanning electron microscope image of a cross section of a cast sheet on the supporting roller side provided by Comparative Example 2;
8 shows a scanning electron microscope image of a cross section of a thin film provided by Comparative Example 2;
Fig. 9 shows a scanning electron microscope image of a cross section of a cast sheet on the supporting roller side provided by Comparative Example 3;
10 shows a scanning electron microscope image of a cross-section of a thin film provided by Comparative Example 3. FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail, examples of which are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are illustrative, and are only for interpreting the present invention and should not be construed as limitations on the present invention.

In the description of the present invention, the terms “center”, “longitudinal”, “transverse”, “length”, “width”, “thickness”, “top”, “bottom”, “front”, “back”, “ Left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial” The direction or positional relationship indicated by ”, “circumferential direction”, etc. is based on the direction or positional relationship shown in the drawings, and is only for explaining the present invention and simplifying the description, and the device or element indicated must be in the specified direction It should be understood that this should not be construed as a limitation on the present invention as it does not indicate or imply that it should be constructed and operated in a specific direction.

In addition, the terms “first” and “second” are used only for the purpose of description, and should not be construed as implicitly indicating the relative importance, suggesting, or indicating the number of technical features. Accordingly, a feature defined as “a first” or a “second” may explicitly or implicitly imply one or more of the aforementioned features. In the description of the present invention, unless specifically limited otherwise, the meaning of “many” is two or two or more.

In the present invention, unless otherwise clearly defined or limited, the terms “mounted”, “connected to each other”, “connected”, “fixed” and the like are to be understood in a broad sense, and for example, can be fixedly connected or , may be detachably connected, or may be integrally connected; may be mechanically connected or electrically connected; It may be directly connected, may be indirectly connected through an intermediate medium, or may be a communication between two elements or an interaction relationship between two elements. For those of ordinary skill in the art, specific meanings of the terms in the present invention can be understood based on specific circumstances.

In the present invention, unless explicitly defined or limited otherwise, a first characteristic being “above” or “below” a second characteristic means that the first and second characteristics directly contact, or that the first and second characteristics It may have been indirect contact through this intermediate medium. Further, a first feature being “above,” “above,” and “above” a second feature may mean that the first feature is directly above or obliquely upward of the second feature, or only of the first feature. It indicates that the horizontal height is higher than the second feature. A first feature being “below,” “below,” and “below” a second feature means that the first feature can be directly underneath or obliquely downward of the second feature, or just horizontal of the first feature. indicating that the height is lower than the second characteristic.

Terms used in the text:

“… … “manufactured by” is synonymous with “included”. As used herein, the terms “comprising”, “including”, “including”, “containing” or other variations thereof are intended to include non-exclusive inclusions. For example, a composition, step, method, article, or device comprising a listed element is not necessarily limited to that element, but other elements not explicitly listed or elements unique to such composition, step, method, article, or device. may include

conjunction"… … “consisting of” excludes any unspecified element, step or ingredient. When used in the claims, this wording renders the claims closed-ended so that they do not include materials other than those described, but exclude related common impurities. Phrases"… … Where “consisting of” appears in a phrase of a claim rather than immediately after the subject, it limits only the elements set forth in that phrase; Other elements are not excluded from the claims as a whole.

When an equivalent, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, this means any upper or lower limit of the range, whether or not that range is separately disclosed. It is to be understood that the preferred value discloses any range formed by arbitrarily matching the lower limit or preferred value of any range. For example, if you publish a range “1-5”, the described range would be the ranges “1-4”, “1-3”, “1-2”, “1-2 and 4-5”, “1 It should be construed as including ~3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the ranges are intended to include the final values and all integers and fractions within the range.

In these examples, all parts and percentages are by mass, unless otherwise specified.

“Part by mass” refers to the basic unit of measurement that expresses the mass ratio relationship of several components, and one part can represent any unit mass, such as 1 g or 2.689 g. If the mass part of component A is a part and the mass part of component B is part b, then the mass ratio of the mass of component A and the mass of component B is a:b. Alternatively, the mass of component A is aK and the mass of component B is bK (K is an arbitrary number and represents a multiple factor). It should not be misunderstood that, unlike the number of parts by mass, the sum of parts by mass of all components is not limited to 100 parts.

“And/or” is used to indicate that one or both of the circumstances described may occur, for example, A and/or B includes (A and B) and (A or B).

Example 1

1 to 6 , an apparatus for manufacturing a high-strength, high-modulus polyolefin thin film includes a twin-screw extruder, a cooling system, a tensioning system, and an extraction system arranged in sequence; The cooling system includes a support roller (1), a shaping roller (2), a cooling roller (3) and a cooling tank (4); The shaping roller (2) is installed between the support roller (1) and the cooling roller (3), and the melt from the die head (5) of the twin screw extruder is on the surface of the shaping roller (2) under the action of the support roller (1) It is attached and moves according to the rotation of the shaping roller 2, and the lower part of the shaping roller 2 is installed in the cooling tank 4 so that the melt can be immersed in the cooling medium of the cooling tank 4; The casting sheet adhered to the surface of the shaping roller 2 is pulled by the cooling roller 3, and a plurality of cooling rollers 3 are wound to achieve the purpose of further cooling the casting sheet. The tensioning system comprises a longitudinal tensioner (including a preheat roller (6), a tensioning roller (7) and a longitudinal tensioner shaping roller (8)), a transverse tensioner and for cutting thin films tensioned by a transverse tensioner. a slitting machine (9), wherein the transverse tensioner is equipped with a heating oven (10) and a cooling oven (11); The temperature accuracy of the heating oven 10 is ±0.5° C., and the uniformity of the wind speed is ±1 m/s. The brewing system comprises five groups of brewing tanks 12 , and all three groups of drafting rollers 13 and two ultrasonic generators 14 are installed in each group of brewing tanks 12 .

First, polyethylene and white oil with a solid content of 25% are put into a twin-screw extruder through a powder scale and a plunger pump, respectively, and are melt-plasticized under the condition of 190°C. The melt is extruded from the die head 5 to form a sheet shape, and the gel-like sheet is immediately formed into a preset gap between the shaping roller 2 and the support roller 1 of the casting machine (the surface temperature of the shaping roller and the support roller is 16 ° C.) ), the cooling tank 4 (cooling medium is water) is increased to forcibly cool the back side of the melt, the temperature of the cooling tank 4 is 20° C., and it is molded into a cast sheet with a thickness of 3.9 mm. The cast sheet is tensioned 6 times along the machine direction (MD) at 100° C. using a longitudinal tensioner, and again tensioned 6 times at 120° C. along the width direction (TD) using a transverse tensioner. Then, after cutting the edge of the oil film formed by tensioning, it is divided into three parts using a slitting machine, the width of each part is 800 mm, and the oil film on both sides using the steering device 15 2 longitudinal tensioners arranged), stretched 1.4 times along the machine direction (MD) at 100°C, and again enters the second transverse tensioner (two front and rear transverse tensioners are arranged) in the transverse direction (TD) is stretched 6 times at 120°C along the It is stretched 6 times at 120°C. Then, the oil film stretched in both directions is passed through the extraction tank 12 containing dichloromethane to extract the white oil of the oil film and dry the oil film. The obtained dried microporous thin film enters the third transverse tensioning machine, is stretched 1.3 times along the TD direction at 130° C., and then shrunk 1.1 times along the TD direction, and at the same time thermally formed at 133° C. Next, it is wound with a winding roll to obtain a polyethylene microporous thin film having a thickness of 7.4 μm.

The thickness, tensile strength, puncture strength, porosity, breathability and heat shrinkage of the prepared polyethylene microporous thin film were measured, respectively, and the measurement results of the obtained polyolefin microporous thin film properties are shown in Table 1.

Example 2

1 to 6 , an apparatus for manufacturing a high-strength, high-modulus polyolefin thin film includes a twin-screw extruder, a cooling system, a tensioning system, and an extraction system arranged in sequence; The cooling system includes a support roller (1), a shaping roller (2), a cooling roller (3) and a cooling tank (4); The shaping roller (2) is installed between the support roller (1) and the cooling roller (3), and the melt from the die head (5) of the twin screw extruder is on the surface of the shaping roller (2) under the action of the support roller (1) It is attached and moves according to the rotation of the shaping roller 2, and the lower part of the shaping roller 2 is installed in the cooling tank 4 so that the melt can be immersed in the cooling medium of the cooling tank 4; The casting sheet adhered to the surface of the shaping roller 2 is pulled by the cooling roller 3, and a plurality of cooling rollers 3 are wound to achieve the purpose of further cooling the casting sheet. The tensioning system comprises a longitudinal tensioner (including preheat rollers 6, tension rollers 7 and longitudinal tensioner shaping rollers 8), a transverse tensioner and a slitting machine 9, The machine is provided with a heating oven 10 and a cooling oven 11 . The temperature accuracy of the heating oven 10 is ±0.5° C., and the uniformity of the wind speed is ±1 m/s. The brewing system comprises five groups of brewing tanks 12 , and all three groups of drafting rollers 13 and two ultrasonic generators 14 are installed in each group of brewing tanks 12 .

First, polyethylene and white oil with a solid content of 25% are put into a twin-screw extruder through a powder scale and a plunger pump, respectively, and are melt-plasticized under the condition of 190°C. The melt is extruded from the die head 5 to form a sheet shape, and the gel-like sheet is immediately formed into a preset gap between the shaping roller 2 and the support roller 1 of the casting machine (the surface temperature of the shaping roller and the support roller is 16 ° C.) ), the cooling tank 4 (cooling medium is water) is increased to forcibly cool the back side of the melt, the temperature of the cooling tank 4 is 20° C., and it is molded into a cast sheet with a thickness of 4.4 mm. The cast sheet is tensioned 6 times along the machine direction (MD) at 100° C. using a longitudinal tensioner, and again tensioned 6 times at 120° C. along the width direction (TD) using a transverse tensioner. Then, after cutting the edge of the oil film formed by tensioning, it is divided into three parts, the width of each part is 800mm, and using the steering device 15, the oil film on both sides is transverse tensioner (front and rear two transverse tensioners) and stretched 6 times at 120°C along the width direction (TD), and the oil film in the middle part directly enters the second transverse tensioner and is stretched 6 times at 120°C along the width direction (TD). Then, the oil film stretched in both directions is passed through the extraction tank 12 containing dichloromethane to extract the white oil of the oil film and dry the oil film. The obtained dried microporous thin film enters the third transverse tensioning machine, is stretched 1.3 times along the TD direction at 130° C., and then shrunk 1.1 times along the TD direction, and at the same time thermally formed at 133° C. Next, it is wound with a winding roll to obtain a polyethylene microporous thin film having a thickness of 9 μm.

The thickness, tensile strength, puncture strength, porosity, breathability and heat shrinkage of the prepared polyethylene microporous thin film were measured, respectively, and the measurement results of the obtained polyolefin microporous thin film properties are shown in Table 1.

Example 3

1 to 6 , an apparatus for manufacturing a high-strength, high-modulus polyolefin thin film includes a twin-screw extruder, a cooling system, a tensioning system, and an extraction system arranged in sequence; The cooling system includes a support roller (1), a shaping roller (2), a cooling roller (3) and a cooling tank (4); The shaping roller (2) is installed between the support roller (1) and the cooling roller (3), and the melt from the die head (5) of the twin screw extruder is on the surface of the shaping roller (2) under the action of the support roller (1) It is attached and moves according to the rotation of the shaping roller 2, and the lower part of the shaping roller 2 is installed in the cooling tank 4 so that the melt can be immersed in the cooling medium of the cooling tank 4; The casting sheet adhered to the surface of the shaping roller 2 is pulled by the cooling roller 3, and a plurality of cooling rollers 3 are wound to achieve the purpose of further cooling the casting sheet. The tensioning system comprises a longitudinal tensioner (including a preheat roller (6), tension roller (7) and a longitudinal tensioner shaping roller (8)), a transverse tensioner and for cutting thin films tensioned by a transverse tensioner. It includes a slitter 9, a steering device 15 and a bidirectional synchronous tensioner 16, wherein both the transverse tensioner and the bidirectional synchronous tensioner 16 are equipped with a heating oven 10 and a cooling oven 11 become; The steering device 15 is installed between the transverse tensioner and the bidirectional synchronous tensioner 16; The bidirectional synchronous tensioner 16 is stacked in three along the height direction; The temperature accuracy of the heating oven 10 is ±0.5° C., and the uniformity of the wind speed is ±1 m/s. The brewing system comprises five groups of brewing tanks 12 , and all three groups of drafting rollers 13 and two ultrasonic generators 14 are installed in each group of brewing tanks 12 .

First, polyethylene and white oil with a solid content of 25% are put into a twin-screw extruder through a powder scale and a plunger pump, respectively, and are melt-plasticized under the condition of 190°C. The melt is extruded from the die head 5 to form a sheet shape, and the gel-like sheet is immediately formed into a preset gap between the shaping roller 2 and the support roller 1 of the casting machine (the surface temperature of the shaping roller and the support roller is 16 ° C.) ), the cooling tank 4 (cooling medium is water) is increased to forcibly cool the back side of the melt, the temperature of the cooling tank 4 is 20° C., and it is molded into a cast sheet with a thickness of 4.3 mm. The cast sheet is tensioned 6 times along the machine direction (MD) at 100° C. using a longitudinal tensioner, and again tensioned 6 times at 120° C. along the width direction (TD) using a transverse tensioner. Then, after cutting the edge of the oil film formed by tensioning, it is divided into three parts, the width of each part is 800mm, and the oil film on both sides is introduced into the two-way synchronous tensioner 16 by using the steering device 15, The oil film in the middle part is introduced into the middle bidirectional synchronous tensioner 16, and it is stretched 6 times simultaneously in the machine direction (MD) and the width direction (TD) at 120°C. Then, the oil film stretched in both directions is passed through the extraction tank 12 containing dichloromethane to extract the white oil of the oil film and dry the oil film. The obtained dried microporous thin film enters a transverse tensioning machine, stretches 1.3 times along the TD direction at 130°C, and then shrinks again along the TD direction by 1.1 times, and is thermally formed at 133°C. Next, it is wound with a winding roll to obtain a polyethylene microporous thin film having a thickness of 3.3 μm.

The thickness, tensile strength, puncture strength, porosity, breathability and heat shrinkage of the prepared polyethylene microporous thin film were measured, respectively, and the measurement results of the obtained polyolefin microporous thin film properties are shown in Table 1.

Table 1 Example test results

In order to better prove the advantageous effect of the present invention, a comparative experiment was conducted as follows.

Comparative Example 1

First, polyethylene and white oil with a solid content of 25% are put into a twin-screw extruder through a powder scale and a plunger pump, respectively, and are melt-plasticized under the condition of 190°C. The melt is extruded from the die to form a sheet form, and immediately the gel-like sheet is passed through a preset gap between the shaping roller and the support roller of the casting machine (the surface temperature of the shaping roller and the support roller is 16°C), the thickness of which is 1.4 mm It is molded into a cast sheet. The cast sheet is tensioned 7 times along the machine direction (MD) at 100° C. using a longitudinal tensioner, and again tensioned 7.5 times along the width direction (TD) using a transverse tensioner. Then, the oil film formed by stretching is passed through an extraction tank containing dichloromethane to extract the white oil of the oil film, and the oil film is dried. The obtained dried microporous thin film enters a transverse tensioning machine, stretches 1.3 times along the TD direction at 130°C, and then shrinks again along the TD direction by 1.1 times, and is thermally formed at 133°C. Next, it is wound with a winding roll to obtain a polyethylene microporous thin film having a thickness of 7 μm.

The thickness, tensile strength, puncture strength, porosity, air permeability and heat shrinkage of the prepared polyethylene microporous thin film were measured, respectively, and the measurement results of the obtained polyolefin microporous thin film properties are shown in Table 2.

Comparative Example 2

On the basis of Comparative Example 1, the input amount of polyethylene and white oil was increased, the thickness of the cast sheet was adjusted to 3.2 mm, and the cast sheet was stretched 7 times along the machine direction (MD) at 100° C. using a longitudinal tensioner, and , after stretching 7.5 times along the width direction (TD) using a transverse tensioner again, a polyethylene microporous thin film having a thickness of 20 μm can be prepared along the stretch. The thickness, tensile strength, puncture strength, porosity, air permeability and heat shrinkage of the prepared polyethylene microporous thin film were measured, respectively, and the measurement results of the properties of the obtained polyolefin microporous thin film are shown in Table 2.

In Comparative Example 2, the cross section of the cast sheet on the supporting roller side is as shown in FIG. 7, and the cross section of the obtained thin film is as shown in FIG.

As can be seen from FIGS. 7 and 8, in the casting sheet and thin film obtained in Comparative Example 2, the cooling effect on the supporting roller surface and the inside of the casting sheet is not good, and the hole structure inside the thin film after tensioning into the thin film is large, so that the battery Short-circuit rate increases after being manufactured with

Comparative Example 3

On the basis of Comparative Example 2, the melt is extruded from the die to form a sheet form, and immediately pass the gel-like sheet through a preset gap between the shaping roller and the support roller of the casting machine (the surface temperature of the shaping roller and the support roller is 16° C.) The cooling tank (cooling medium is water) is increased to forcibly cool the back side of the melt, and the temperature of the cooling tank is 20° C., and it is molded into a casting sheet with a thickness of 3.1 mm. Other tasks are not changed. The thickness, tensile strength, puncture strength, porosity, air permeability and heat shrinkage of the prepared polyethylene microporous thin film were measured, respectively, and the measurement results of the properties of the obtained polyolefin microporous thin film are shown in Table 2. In Comparative Example 3, the cross section of the cast sheet on the supporting roller side is as shown in FIG. 9, and the cross section of the obtained thin film is as shown in FIG.

As can be seen from the comparison of Figs. 7 and 9, Fig. 8 and Fig. 10, using the cooling system of support roller + shaping roller + cooling roller + cooling tank provided by the present invention, the resulting cast sheet becomes remarkably dense and After being stretched into a thin film, the structure inside the diaphragm becomes very dense, greatly improving the safety of the diaphragm and the consistency of the performance of the diaphragm.

Table 2 Comparative Example Test Results

As can be seen by comparing the data in Tables 1 and 2, using the apparatus and method provided by the present invention, the strength and modulus of the diaphragm produced by multi-step bidirectional tensile is significantly improved compared to the conventional process, and the thickness and The extreme difference in ventilation value is very small, and the uniformity of the diaphragm is greatly improved.

The present invention combines multiple longitudinal, transverse or bidirectional tensile machines using an ultra-high tensile multiplier process design to perform multiple overlap tensile to form a tensile multiplier that far exceeds that of conventional conventional tensile machines, and the area tensile multiplier is It is greatly improved to the level of 100*100 times, and in this way, the orientation, crystallization, fiber refining, and specific strength of the thin film material are greatly improved, and the breaking tensile rate of the thin film material is reduced to form an ultra-high modulus polyolefin thin film material exceeding 10 GPa. do. The material can be widely used in the field of lithium battery diaphragm, air filtration membrane, water treatment membrane, yushu separator, high-strength, high-modulus thin film material lining for safety protection equipment, and has huge technical advantages and application space.

In the description of this specification, reference terms such as “one embodiment”, “some embodiments”, “examples”, “specific examples”, or “some examples” refer to specific features described in connection with the embodiments or examples. , a structure, material, or feature is included in at least one embodiment or illustration of the present invention. In this specification, exemplary expressions for the above terms do not necessarily refer to the same embodiment or example. In addition, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or multiple embodiments or examples. In addition, as long as there is no conflict with each other, a person of ordinary skill in the art may combine and combine different embodiments or examples and features of different embodiments or examples described herein.

The embodiments of the present invention have been illustrated and described above, but the embodiments are merely exemplary and should not be construed as limitations on the present invention, and those of ordinary skill in the art will recognize the above embodiments within the scope of the present invention. may be altered, modified, substituted, and altered.

1: support roller
2: Orthopedic roller
3: Cooling roller
4: cooling tank
5: die head
6: Preheat roller
7: Tension roller
8: Longitudinal Tensioner Forming Roller
9: Slitting machine
10: heating oven
11: cooling oven
12: brew tank
13: drafting roller
14: ultrasonic generator
15: steering device
16: Bi-directional synchronous tensioner

Claims (10)

In an apparatus for manufacturing a high-strength, high-modulus polyolefin thin film,
a sequentially disposed melt extruder, a cooling system, a tensioning system and an extraction system;
The tensioning system includes a transverse tensioner for transversely tensioning an object to be tensioned, a longitudinal tensioner for tensioning the object to be tensioned in the longitudinal direction, a slitter for cutting the object to be tensioned, and a bidirectional tensioner for tensioning the object to be tensioned in both directions. An apparatus for producing a high-strength, high-modulus polyolefin thin film comprising a plurality in a synchronous tensioner. According to claim 1,
The cooling system includes a support roller, a shaping roller, a cooling roller and a cooling tank;
The shaping roller is installed between the support roller and the cooling roller, the support roller is for attaching the melt from the die head of the melt extruder to the surface of the shaping roller, the lower part of the shaping roller is the cooling tank It is installed in, and the cooling roller is an apparatus for producing a high-strength, high-modulus polyolefin thin film, characterized in that for cooling the cast sheet processed by the shaping roller. According to claim 1,
said tensioning system comprising said longitudinal tensioner, said transverse tensioner, said slitting machine and said bidirectional synchronous tensioner installed sequentially; The slitting machine is a device for producing a high-strength, high-modulus polyolefin thin film, characterized in that for cutting the thin film stretched by the transverse tensioner. According to claim 1,
Further comprising a steering device installed behind the slitting machine;
Preferably, the bidirectional synchronous tensioner is installed in plurality;
Preferably, the two-way synchronous tensioner is installed in three stacks along the height direction;
Preferably, a heating oven and a cooling oven are installed in the bidirectional synchronous tensioner, the temperature accuracy of the heating oven is ±0.5°C, and the uniformity of the wind speed is ±1m/s. manufacturing equipment. 5. The method according to any one of claims 1 to 4,
The extraction system includes one group or several groups of extraction tanks, and several groups of drafting rollers and ultrasonic generators are installed in the extraction tanks for each group. device that does. The polyolefin resin and solvent are melt plasticized in a melt extruder, extruded through a die head, and then heat-induced phase separation is achieved in a shaping roller and a cooling tank to obtain a cast sheet, which is then tensioned by a multi-stage combination of tensioning system, extracted by an extraction system and A method for producing a high-strength, high-modulus polyolefin thin film, comprising the step of obtaining the high-strength, high-modulus polyolefin thin film through post-treatment. 7. The method of claim 6,
The method for producing a high-strength, high-modulus polyolefin thin film, characterized in that the thickness of the melt extruded by the die head is 2mm-10mm. 7. The method of claim 6,
The tensioning method of the tensioning system is,
sequentially performing longitudinal tension 1-10 times, transverse tension 1-10 times and bidirectional synchronous tension (1-10)*(1-10) times; or,
sequentially performing 1-10 times longitudinal tension, 1-10 times transverse tension, and repeatedly performing 1-10 times longitudinal tension and 1-10 times transverse tension once; or,
Two consecutive independent bidirectional synchronous tensioning (1-10)*(1-10) folds; or,
A high-strength, high-modulus polyolefin thin film comprising sequentially performing bidirectional synchronous tensile (1-10) * (1-10) times, longitudinal tensile 1-10 times, and transverse tensile 1-10 times How to manufacture. 9. The method according to any one of claims 6 to 8,
The post-treatment includes drying, transverse expansion tensile, longitudinal and transverse bidirectional shrinkage treatment, and thermal forming, which are sequentially performed;
Preferably, when performing the extraction, a method for producing a high-strength, high-modulus polyolefin thin film, characterized in that the tensile pieces are not cut in advance. In the high-strength, high-modulus polyolefin thin film produced by the method for manufacturing the high-strength, high-modulus polyolefin thin film according to any one of claims 6 to 9,
Preferably, the thickness of the high-strength, high-modulus polyolefin thin film is 2-100 μm, the air permeability is 10-300 s/in ² * 100 cc, the tensile strength is 300-2000 MPa, the non-puncture strength is 50-300 gf/μm, and the porosity is is 25-75%, and the modulus is a high strength, high modulus polyolefin thin film, characterized in that it is 2 GPa ~ 30 GPa.

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